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| United States Patent |
5,641,393
|
|
Nakagawa
|
June 24, 1997
|
High-silica zeolite SSZ-37 and methods of making and using same
Abstract
A crystalline zeolite high-silica SSZ-37 is prepared using a
N,N-dimethyl-4-azoniatricyclo [5.2.2.0.sup.(2,6) ] undec-8-ene cation as a
template wherein said zeolite is used in hydrocarbon conversion processes.
| Inventors:
|
Nakagawa; Yumi (Oakland, CA)
|
| Assignee:
|
Chevron U.S.A. Inc. (San Francisco, CA)
|
| Appl. No.:
|
512603 |
| Filed:
|
August 8, 1995 |
| Current U.S. Class: |
208/46; 208/28; 208/109; 208/111.15; 208/111.25; 208/111.35; 208/118; 502/61; 502/62; 502/64; 502/65; 502/66; 585/418; 585/420; 585/446; 585/481; 585/533; 585/640; 585/733; 585/739; 585/752 |
| Intern'l Class: |
C10G 011/05; C10G 047/16; C10G 003/00; B01J 029/04 |
| Field of Search: |
502/62,61,64,65,66
423/709,718
208/111,114,118,124,120,137,138,28,46,58,109
585/407,446,533,733,752,739,418,420,481
|
References Cited
U.S. Patent Documents
| 4589976 | May., 1986 | Zones | 208/111.
|
| 4589977 | May., 1986 | Zones | 208/111.
|
| 4963337 | Oct., 1990 | Zones | 423/277.
|
| 5041402 | Aug., 1991 | Casci et al. | 502/67.
|
| 5102641 | Apr., 1992 | Casci et al. | 423/328.
|
| 5178748 | Jan., 1993 | Casci et al. | 208/46.
|
| 5202014 | Apr., 1993 | Zones et al. | 208/46.
|
| 5254514 | Oct., 1993 | Nakagawa | 502/62.
|
| 5254787 | Oct., 1993 | Dessau | 585/654.
|
| 5271921 | Dec., 1993 | Nakagawa | 423/702.
|
| 5273736 | Dec., 1993 | Nakagawa | 423/702.
|
| 5345021 | Sep., 1994 | Casci et al. | 585/467.
|
Primary Examiner: Caldarola; Glenn A.
Assistant Examiner: Yildirim; Bekir L.
Attorney, Agent or Firm: Sheridan; R. J.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No.
08/380,233, filed Jan. 30, 1995, which is a continuation of Ser. No.
08/243,603, filed May. 16, 1994 (now abandoned), which is a continuation
of Ser. No. 08/095,771, filed Jul. 21, 1993 (now abandoned), which is a 16
division of Ser. No. 07/906,919, filed Jun. 30, 1992 (now U.S. Pat. No.
5,254,514).
Claims
What is claimed is:
1. A zeolite having a mole ratio of an oxide selected from silicon oxide,
germanium oxide and mixtures thereof to an oxide selected from aluminum
oxide, boron oxide, gallium oxide, iron oxide and mixtures thereof greater
than 400 and having, after calcination, the X-ray diffraction lines of
Table II.
2. A zeolite having a composition, as synthesized and in the anhydrous
state, in terms of mole ratios of oxides as follows:
______________________________________
YO.sub.2 /W.sub.2 O.sub.3
>400
Q/YO.sub.2 0.02-0.10
M.sub.2 O/YO.sub.2
0.001-0.005
______________________________________
wherein M is an alkali metal cation, W is selected from aluminum, boron,
gallium, iron and mixtures thereof, Y is selected from silicon, germanium
and mixtures thereof, and Q is an N,N-dimethyl-4-azoniatricyclo
[5.2.2.0.sup.(2,6) ] undec-8-ene cation and having the X-ray diffraction
lines of Table I.
3. The zeolite according to claim 1 or 2 wherein W is aluminum and Y is
silicon.
4. The zeolite according to claim 1 or 2 wherein said mole ratio of silicon
oxide or germanium oxide to aluminum oxide, gallium oxide, or iron oxide
is 450 or greater.
5. The zeolite according to claim 1 or 2 wherein said mole ratio of silicon
oxide or germanium oxide to aluminum oxide, gallium oxide, or iron oxide
is 600 or greater.
6. The zeolite according to claim 1 or 2 wherein said mole ratio of silicon
oxide or germanium oxide to aluminum oxide, gallium oxide, or iron oxide
is 1000 or greater.
7. The zeolite according to claim 1 or 2 which is essentially free of
oxides selected from aluminum oxide, boron oxide, gallium oxide and iron
oxide.
8. A zeolite according to claim 1 which has undergone ion exchange with
hydrogen, ammonium, rare earth metal, Group IIA metal, or Group VIII metal
ions.
9. A zeolite according to claim 1 wherein rare earth metals, Group IIA
metals, or Group VIII metals are occluded in the zeolite.
10. A method for preparing a zeolite having a mole ratio of an oxide
selected from silicon oxide, germanium oxide and mixtures thereof to an
oxide selected from aluminum oxide, boron oxide, gallium oxide, iron oxide
and mixtures thereof greater than 400 and having, after calcination, the
X-ray diffraction lines of Table II, said method comprising:
(a) preparing an aqueous mixture containing sources of an alkali metal
oxide, an N,N-dimethyl-4-azoniatricyclo [5.2.2.0.sup.(2,6) ] undec-8-ene
cation, an oxide selected from aluminum oxide, boron oxide, gallium oxide,
iron oxide and mixtures thereof, an oxide selected from silicon oxide,
germanium oxide and mixtures thereof, and seed crystals of a crystalline
material capable of initiating formation of said zeolite;
(b) maintaining the mixture at a temperature of at least 140.degree. C.
until crystals of said zeolite form; and
(c) recovering said crystals.
11. The method according to claim 10 wherein the aqueous mixture has a
composition in terms of mole ratios falling in the ranges:
YO.sub.2 /W.sub.2 O.sub.3 >400
OH.sup.- /YO.sub.2 0.10-0.50
Q/YO.sub.2 0.10-0.30
M.sup.+ /YO.sub.2 0.01-0.30
H.sub.2 O/YO.sub.2 15-50
wherein Q is N,N-dimethyl-4-azoniatricyclo [5.2.2.0.sup.(2,6) ]
undec-8-ene, Y is selected from silicon, germanium and mixtures thereof, W
is selected from aluminum, boron, gallium, iron and mixtures thereof, and
M is an alkali metal cation.
12. The method according to claim 11 wherein the aqueous mixture has a
composition in terms of mole ratios falling in the ranges:
______________________________________
YO.sub.2 /W.sub.2 O.sub.3
.infin.
OH.sup.- /YO.sub.2
0.20-0.30
Q/YO.sub.2
0.15-0.25
M.sup.+ /YO.sub.2
0.05-0.15
H.sub.2 O/YO.sub.2
30-45
______________________________________
13. The method according to claim 11 wherein the zeolite is a borosilicate
and the aqueous mixture has a composition in terms of mole ratios falling
in the ranges:
YO.sub.2 /W'.sub.2 O.sub.3 >400
YO.sub.2 /B.sub.2 O.sub.3 >400
OH.sup.- /YO.sub.2 0.10-0.5.
Q/YO.sub.2 0.10-0.30
M.sup.+ /YO.sub.2 0.01-0.30
H.sub.2 O/YO.sub.2 15-50
wherein Y, Q and M are as defined in claim 11 and W' is selected from
aluminum, gallium, iron and mixtures thereof.
14. The method according to claim 13 wherein the aqueous mixture has a
composition in terms of mole ratios falling in the ranges:
______________________________________
YO.sub.2 /W'.sub.2 O.sub.3
.infin.
YO.sub.2 /B.sub.2 O.sub.3
>40
OH.sup.- /YO.sub.2
0.20-0.30
Q/YO.sub.2 0.15-0.25
M.sup.+ /YO.sub.2
0.05-0.15
H.sub.2 O/YO.sub.2
30-45
______________________________________
15. The method according to claim 11 wherein Y is silicon and W is
aluminum.
16. A process for converting hydrocarbons comprising contacting a
hydrocarbonaceous feed at hydrocarbon converting conditions with a
catalyst comprising a zeolite having a mole ratio of an oxide selected
from silicon oxide, germanium oxide and mixtures thereof to an oxide
selected from aluminum oxide, boron oxide, gallium oxide, iron oxide and
mixtures thereof greater than 400 and having, after calcination, the X-ray
diffraction lines of Table II.
17. The process of claim 16 which is a hydrocracking process comprising
contacting the hydrocarbon feedstock under hydrocracking conditions with a
catalyst comprising a zeolite having a mole ratio of an oxide selected
from silicon oxide, germanium oxide and mixtures thereof to an oxide
selected from aluminum oxide, boron oxide, gallium oxide, iron oxide and
mixtures thereof greater than 400 and having, after calcination, the X-ray
diffraction lines of Table II and a Group VIII metal.
18. The process of claim 16 which is a dewaxing process comprising
contacting the hydrocarbon feedstock under dewaxing conditions with a
catalyst comprising a zeolite having a mole ratio of an oxide selected
from silicon oxide, germanium oxide and mixtures thereof to an oxide
selected from aluminum oxide, boron oxide, gallium oxide, iron oxide and
mixtures thereof greater than 400 and having, after calcination, the X-ray
diffraction lines of Table II.
19. The process of claim 16 which is a process for preparing a high octane
product having an increased aromatics content comprising:
(a) contacting a hydrocarbonaceous feed which comprises normal and slightly
branched hydrocarbons having a boiling range above about 40.degree. C. and
less than about 200.degree. C., under aromatic conversion conditions with
a catalyst comprising a zeolite having a mole ratio of an oxide selected
from silicon oxide, germanium oxide and mixtures thereof to an oxide
selected from aluminum oxide, boron oxide, gallium oxide, iron oxide and
mixtures thereof greater than 400 and having, after calcination, the X-ray
diffraction lines of Table II, wherein said zeolite is substantially free
of acidity; and
(b) recovering a product with higher octane and higher aromatic content.
20. The process of claim 19 wherein the zeolite contains a Group VIII metal
component.
21. The process of claim 16 which is a catalytic cracking process
comprising the step of contacting the hydrocarbon feedstock in a reaction
zone under catalytic cracking conditions in the absence of added hydrogen
with a catalyst comprising a zeolite having a mole ratio of an oxide
selected from silicon oxide, germanium oxide and mixtures thereof to an
oxide selected from aluminum oxide, boron oxide, gallium oxide, iron oxide
and mixtures thereof greater than 400 and having, after calcination, the
X-ray diffraction lines of Table II.
22. The process according to claim 21 wherein the catalyst contains a large
pore size crystalline aluminosilicate cracking component.
23. The process of claim 16 which is an isomerizing process for isomerizing
C.sub.4 to C.sub.7 hydrocarbons, comprising contacting a catalyst,
comprising at least one Group VIII metal and a zeolite having a mole ratio
of an oxide selected from silicon oxide, germanium oxide and mixtures
thereof to an oxide selected from aluminum oxide, boron oxide, gallium
oxide, iron oxide and mixtures thereof greater than 400 and having, after
calcination, the X-ray diffraction lines of Table II, with a feed having
normal and slightly branched C.sub.4 to C.sub.7 hydrocarbons under
isomerization conditions.
24. A process in accordance with claim 23 wherein the catalyst has been
calcined in a steam/air mixture at an elevated temperature after
impregnation of the Group VIII metal.
25. A process in accordance with claim 24 wherein the Group VIII metal is
platinum.
26. The process of claim 16 which is a process for alkylating an aromatic
hydrocarbon which comprises contacting under alkylating conditions at
least a mole excess of an aromatic hydrocarbon with a C.sub.2 to C.sub.4
olefin under at least partial liquid phase conditions and in the presence
of a catalyst comprising a zeolite having a mole ratio of an oxide
selected from silicon oxide, germanium oxide and mixtures thereof to an
oxide selected from aluminum oxide, boron oxide, gallium oxide, iron oxide
and mixtures thereof greater than 400 and having, after calcination, the
X-ray diffraction lines of Table II.
27. The process of claim 26 wherein the aromatic hydrocarbon and olefin are
present in a molar ratio of about 4:1 to 20:1, respectively.
28. The process of claim 26 wherein the aromatic hydrocarbon is a member
selected from the group consisting of benzene, toluene and xylene, or
mixtures thereof.
29. The process of claim 16 which is a process for transalkylating an
aromatic hydrocarbon which comprises contacting under transalkylating
condition an aromatic hydrocarbon with a polyalkyl aromatic hydrocarbon
under at least partial liquid phase conditions and in the presence of a
catalyst comprising a zeolite having a mole ratio of an oxide selected
from silicon oxide, germanium oxide and mixtures thereof to an oxide
selected from aluminum oxide, boron oxide, gallium oxide, iron oxide and
mixtures thereof greater than 400 and having, after calcination, the X-ray
diffraction lines of Table II.
30. The process of claim 29 wherein said aromatic hydrocarbon and said
polyalkyl aromatic hydrocarbon are present in a molar ratio of about 1:1
to about 25:1, respectively.
31. The process of claim 29 wherein the aromatic hydrocarbon is a member
selected from the group consisting of benzene, toluene and xylene, or
mixtures thereof.
32. The process of claim 29 wherein the polyalkyl aromatic hydrocarbon is
dialkylbenzene.
33. A process in accordance with claim 16 wherein the process comprises:
(a) contacting a hydrocarbonaceous feed, which comprises normal and
slightly branched hydrocarbons having a boiling range above about
40.degree. C. and less than about 200.degree. C. under aromatic conversion
conditions with a catalyst comprising a zeolite having a mole ratio of an
oxide selected from silicon oxide, germanium oxide and mixtures thereof to
an oxide selected from aluminum oxide, boron oxide, gallium oxide, iron
oxide and mixtures thereof greater than 400 and having, after calcination,
the X-ray diffraction lines of Table II; and
(b) recovering an aromatic-containing effluent.
34. The process in accordance with claim 16 wherein the process is a
process for converting a C.sub.2 -C.sub.6 olefin or paraffin feedstream to
aromatic compounds comprising contacting the feed material under aromatic
conversion conditions with a catalyst comprising a zeolite having a mole
ratio of an oxide selected from silicon oxide, germanium oxide and
mixtures thereof to an oxide selected from aluminum oxide, boron oxide,
gallium oxide, iron oxide and mixtures thereof greater than 400 and
having, after calcination, the X-ray diffraction lines of Table II.
35. The process of claim 16 which is an isomerization process for
isomerizing xylenes, comprising contacting a catalyst, comprising at least
one Group VIII metal and a zeolite having a mole ratio of an oxide
selected from silicon oxide, germanium oxide and mixtures thereof to an
oxide selected from aluminum oxide, boron oxide, gallium oxide, iron oxide
and mixtures thereof greater than 400 and having, after calcination, the
X-ray diffraction lines of Table II, with a hydrocarbon feed having
xylenes under isomerization conditions.
36. The process of claim 16 which is a dehydrogenation process for the
dehydrogenation of alkanes, comprising contacting an alkane, under
dehydrogenation conditions, with a catalyst comprising at least one Group
VIII metal and a zeolite having a mole ratio of an oxide selected from
silicon oxide, germanium oxide and mixtures thereof to an oxide selected
from aluminum oxide, boron oxide, gallium oxide, iron oxide and mixtures
thereof greater than 400 and having, after calcination, the X-ray
diffraction lines of Table II.
37. A process for the conversion of lower aliphatic alcohols having 1 to 8
carbon atoms to form gasoline boiling range hydrocarbons which comprises
contacting the alcohols under converting conditions with a catalyst
comprising a zeolite having a mole ratio of an oxide selected from silicon
oxide, germanium oxide and mixtures thereof to an oxide selected from
aluminum oxide, boron oxide, gallium oxide, iron oxide and mixtures
thereof greater than 400 and having, after calcination, the X-ray
diffraction lines of Table II.
38. The process of claim 37 wherein the alcohol is methanol.
Description
BACKGROUND OF THE INVENTION
U.S. Pat No. 5,254,514, issued Oct. 19, 1993 to Nakagawa, describes the
zeolite known as "SSZ-37". The SSZ-37 is described as having a mole ratio
of an oxide selected from silicon oxide, germanium oxide and mixtures
thereof to an oxide selected from aluminum oxide, boron oxide, gallium
oxide, iron oxide and mixtures thereof between 25:1 and 400:1 and having
characteristic X-ray diffraction lines. U.S. Pat. No. 5,254,514 does not,
however, disclose a high- or all-silica version of SSZ-37.
It is believed that SSZ-37 is related structurally to the zeolite
designated NU-87. U.S. Pat. Nos. 5,041,402; 5,178,748 and 5,345,021, all
to Casci et al., disclose NU-87. This material is said to contain equal to
or less than ten moles of an oxide of aluminum, iron, gallium, boron,
titanium, vanadium, zirconium, molybdenum, arsenic, antimony, chromium or
manganese per 100 moles of an oxide of silicon or germanium. The typical
range of the former group of oxides per 100 moles of silicon or germanium
oxide is said to be in the range of 0.1 to 10, for example 0.2 to 7.5.
NU-87 is also disclosed in U.S. Pat. No. 5,102,641, issued Apr. 7, 1992 to
Casci et al., with the same mole ratios of oxides as disclosed in the
previously mentioned Casci et al. patents.
U.S. Pat. No. 5,254,787, issued Oct. 19, 1993 to Dessau, discloses a
catalytic dehydrogenation and/or dehydrocyclization process using a Group
VIA or Group VIII metal-containing non-acidic zeolite having the structure
of NU-87.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a zeolite
having a mole ratio of an oxide selected from silicon oxide, germanium
oxide and mixtures thereof to an oxide selected from aluminum oxide, boron
oxide, gallium oxide, iron oxide and mixtures thereof greater than 400 and
having, after calcination, the X-ray diffraction lines of Table II.
Also in accordance with the present invention, there is provided a zeolite
having a composition, as synthesized and in the anhydrous state, in terms
of mole ratios of oxides as follows:
______________________________________
YO.sub.2 /W.sub.2 O.sub.3
>400
Q/YO.sub.2 0.02-0.10
M.sub.2 O/YO.sub.2
0.001-0.005
______________________________________
wherein M is an alkali metal cation, W is selected from aluminum, boron,
gallium, iron and mixtures thereof, Y is selected from silicon, germanium
and mixtures thereof, and Q is an N,N-dimethyl-4-azoniatricyclo
[5.2.2.0.sup.(2,6) ] undec-8-ene cation and having the X-ray diffraction
lines of Table I.
Further provided in accordance with this invention is a method for
preparing a zeolite having a mole ratio of an oxide selected from silicon
oxide, germanium oxide and mixtures thereof to an oxide selected from
aluminum oxide, boron oxide, gallium oxide, iron oxide and mixtures
thereof greater than 400 and having, after calcination, the X-ray
diffraction lines of Table II, said method comprising:
(a) preparing an aqueous mixture containing sources of an alkali metal
oxide, an N,N-dimethyl-4-azoniatricyclo [5.2.2.0.sup.(2.6) ] undec-8-ene
cation, an oxide selected from aluminum oxide, boron oxide, gallium oxide,
iron oxide and mixtures thereof, an oxide selected from silicon oxide,
germanium oxide and mixtures thereof, and seed crystals of a crystalline
material capable of initiating formation of said zeolite;
(b) maintaining the mixture at a temperature of at least 140.degree. C.
until crystals of said zeolite form; and
(c) recovering said crystals.
The present invention also provides a process for converting hydrocarbons
comprising contacting a hydrocarbonaceous feed at hydrocarbon converting
conditions with a catalyst comprising a zeolite having a mole ratio of an
oxide selected from silicon oxide, germanium oxide and mixtures thereof to
an oxide selected from aluminum oxide, boron oxide, gallium oxide, iron
oxide and mixtures thereof greater than 400 and having, after calcination,
the X-ray diffraction lines of Table II.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term "high-silica SSZ-37" refers to the zeolite SSZ-37
having a silica to alumina mole ratio of greater than 400, preferably 450
or greater, more preferably 600 or greater, more preferably 1000 or
greater. The term "all-silica SSZ-37" refers to the zeolite SSZ-37 which
is has only silica in its framework structure, i.e., the SSZ-37 is
essentially free of other metal oxides (e.g., alumina) in the framework
structure. The term "essentially free" is used because it is difficult to
prepare reaction mixtures for synthesizing this material which is
completely free of aluminum oxide. Especially when commercial sources of
silica are used, aluminum is almost always present to a greater or lesser
degree. By using "essentially free" it is meant that no aluminum or other
metal is intentionally added to the reaction mixture, e.g., as an alumina
or aluminate reagent, and that to the extent aluminum or another metal is
present, it appears only as a contaminant in the reagents.
High-silica SSZ-37 zeolite can be suitably prepared from an aqueous
solution containing sources of an alkali metal oxide, an
N,N-dimethyl-4-azoniatricyclo [5.2.2.0.sup.(2,6) ] undec-8-ene cation, and
the oxides indicated in Table A below. The reaction mixture should have a
composition in terms of mole ratios falling within the following ranges:
TABLE A
______________________________________
Reaction Mixture for High-Silica SSZ-37
Broad Preferred
______________________________________
YO.sub.2 /W.sub.2 O.sub.3
>400 .infin.
OH.sup.- /YO.sub.2
0.10-0.50
0.20-0.30
Q/YO.sub.2 0.10-0.30
0.15-0.25
M.sup.+ /YO.sub.2
0.01-0.30
0.05-0.15
H.sub.2 O/YO.sub.2
15-50 30-45
______________________________________
wherein M is an alkali metal cation (preferably sodium), W is selected from
aluminum, boron, gallium, iron and mixtures thereof, Y is selected from
silicon, germanium and mixtures thereof, and Q is an
N,N-dimethyl-4-azoniatricyclo [5.2.2.0.sup.(2.6) ] undec-8-ene cation.
Anions which are associated with the organic cation are those which are
not detrimental to the formation of the zeolite.
When (B)SSZ-37 is the desired product, the reaction mixture should have a
composition in terms of mole ratios falling within the following ranges:
TABLE B
______________________________________
Reaction Mixture for (B)SSZ-37
Broad Preferred
______________________________________
YO.sub.2 /W'.sub.2 O.sub.3
>400 .infin.
YO.sub.2 /B.sub.2 O.sub.3
>30 >40
OH.sup.- /YO.sub.2
0.10-0.50
0.20-0.30
Q/YO.sub.2 0.10-0.30
0.15-0.25
M.sup.+ /YO.sub.2
0.01-0.30
0.05-0.15
H.sub.2 O/YO.sub.2
15-50 30-45
______________________________________
wherein Y, Q and M are as defined above and W' is selected from aluminum,
gallium, iron and mixtures thereof.
The N,N-dimethyl-4-azoniatricyclo [5.2.2.0.sup.(2.6) ] undec-8-ene cation
component Q, of the crystallization mixture, is preferably derived from a
compound of the formula:
##STR1##
wherein A.sup..theta. is an anion which is not detrimental to the
formation of the zeolite. Representative of the anions include halogen,
e.g., fluoride, chloride, bromide and iodide, hydroxide, acetate, sulfate,
tetrafluoroborate, carboxylate, and the like. Hydroxide is the most
preferred anion.
It has been found that the use of seed crystals in the reaction mixture is
required to make high-silica SSZ-37 and (B)SSZ-37. If the above-described
templating agent is used without such seed crystals, the product obtained
may not be the desired one. For example, in the high-silica case, the
product formed (in the absence of seed crystals) is the zeolite SSZ-31. In
the boron-containing reaction, the product formed (in the absence of seed
crystals) is the zeolite SSZ-33. When seed crystals are used, however, the
respective products are high-silica SSZ-37 and (B)SSZ-37.
The seed crystals are crystals of crystalline materials which are capable
of initiating crystallization of the zeolites of this invention from the
reaction mixtures of this invention. Preferred seed crystals are SSZ-37,
preferably high- or all-silica SSZ-37 or borosilicate SSZ-37. They are
used in an amount ranging from about 0.1 wt % to about 10.0 wt %,
preferably from about 0.5 wt % to about 5.0 wt %, based on the weight of
silica used in the reaction mixture.
The reaction mixture is prepared using standard zeolitic preparation
techniques, such as those described in U.S. Pat. No. 5,254,514 which is
incorporated by reference in its entirety.
Typical sources of silicon oxide include silicates, silica hydrogel,
silicic acid, colloidal silica, fumed silicas, tetraalkyl orthosilicates,
and silica hydroxides. Typical sources of boron oxide include sodium
borate and boric acid.
As-synthesized, high-silica SSZ-37 has a composition, in the anhydrous
state, in terms of mole ratios, shown in Table C below.
TABLE C
______________________________________
As-Synthesized High-Silica SSZ-37
______________________________________
YO.sub.2 /W.sub.2 O.sub.3
>400
Q/YO.sub.2 0.02-0.10
M.sub.2 O/YO.sub.2
0.001-0.005
______________________________________
where Y, W, Q and M are as defined above.
High-silica SSZ-37 zeolite, as synthesized, has a crystalline structure
whose X-ray powder diffraction pattern shows the following characteristic
lines:
TABLE I
______________________________________
As-synthesized high-silica SSZ-37
2 .theta. d/n Rel. Intensity
______________________________________
7.03 12.57 W
7.82 11.29 S-VS
8.28 10.67 W
10.54 8.385 W (Shoulder)
12.92 6.847 W
19.18 4.623 M
20.04 4.426 W-M
20.42 4.346 VS
22.22 3.997 VS
22.66 3.921 W
23.74 3.745 W
25.88 3.440 W-M
26.57 3.353 W
27.12 3.285 S
______________________________________
The X-ray patterns such as that of Table I are based on a relative
intensity scale in which the strongest line in the X-ray pattern is
assigned a value of 100: W(weak) is less than 20; M(medium) is between 20
and 40; S(strong) is between 40 and 60; VS(very strong) is greater than
60.
The variation in the scattering angle (two theta) measurements, due to
instrument error and to differences between individual samples, is
estimated at .+-.0.20 degrees.
The X-ray powder diffraction patterns were determined by standard
techniques. The radiation was the K-alpha/doublet of copper. The peak
heights and the positions, as a function of 2.theta.where .theta. is the
Bragg angle, were read from the relative intensities of the peaks, and d,
the interplanar spacing in Angstroms corresponding to the recorded lines,
can be calculated.
The X-ray diffraction pattern of Table I is characteristic of
as-synthesized high- and all-silica SSZ-37 zeolites. The zeolite produced
by exchanging some of the cations present in the zeolite with various
other cations yields substantially the same diffraction pattern although
there can be minor shifts in interplanar spacing and minor variations in
relative intensity. Minor variations in the diffraction pattern can also
result from variations in the organic compound used in the preparation.
Calcination can also cause minor shifts in the X-ray diffraction pattern.
Notwithstanding these minor perturbations, the basic crystal lattice
structure remains unchanged.
After calcination, the high- and all-silica SSZ-37 zeolite has a
crystalline structure whose X-ray powder diffraction pattern shows the
following characteristic lines as indicated in Table II below:
TABLE II
______________________________________
Calcined All-Silica SSZ-37
2 .theta. d/n Rel. Intensity
______________________________________
7.05 12.53 W
7.94 11.13 VS
8.36 10.57 M
10.63 8.313 W (Shoulder)
12.95 6.832 W
19.29 4.598 M
20.26 4.381 W
20.64 4.301 S
22.39 3.968 W-M
22.78 3.901 W
23.61 3.765 W
26.10 3.412 W
26.74 3.332 W
27.34 3.259 W-M
______________________________________
The synthetic high-silica SSZ-37 zeolite can be used as synthesized or can
be thermally treated (calcined). Usually, it is desirable to remove any
alkali metal cation by ion exchange and replace it with hydrogen,
ammonium, or any desired metal ion. The zeolite can also be steamed;
steaming helps stabilize the crystalline lattice to attack from acids. The
zeolite can be used in intimate combination with hydrogenating components,
such as tungsten, vanadium, molybdenum, rhenium, nickel, cobalt, chromium,
manganese, or a noble metal, such as palladium or platinum, for those
applications in which a hydrogenation-dehydrogenation function is desired.
Typical replacing cations can include metal cations, e.g., rare earth,
Group IA, Group IIA and Group VIII metals, as well as their mixtures. Of
the replacing metallic cations, cations of metals such as rare earth, Fin,
Ca, Mg, Zn, Ga, Cd, Pt, Pd, Ni, Co, Ti, Al, Sn, Fe and Co are particularly
preferred.
The hydrogen, ammonium, and metal components can be exchanged into the
zeolite. The zeolite can also be impregnated with the metals, or the
metals can be physically O8 intimately admixed with the zeolite using
standard methods known to the art. And, the metals can be occluded in the
crystal lattice by having desired metals present as ions in the reaction
mixture from which the high-silica SSZ-37 zeolite is prepared.
Typical ion exchange techniques involve contacting the synthetic zeolite
with a solution containing a salt of the desired replacing cation or
cations. Although a wide variety of salts can be employed, chlorides and
other halides, nitrates, acetates, and sulfates are particularly
preferred. Representative ion exchange techniques are disclosed in a wide
variety of patents including U.S. Pat. Nos. 3,140,249; 3,140,251; and
3,140,253. Ion exchange can take place either before or after the zeolite
is calcined.
Following contact with the salt solution of the desired replacing cation,
the zeolite is typically washed with water and dried at temperatures
ranging from 65.degree. C. to about 315.degree. C. After washing, the
zeolite can be calcined in air or inert gas at temperatures ranging from
about 200.degree. C. to 820.degree. C. for periods of time ranging from 1
to 48 hours, or more, to produce a catalytically active product especially
useful in hydrocarbon conversion processes.
Regardless of the cations present in the synthesized form of the zeolite,
the spatial arrangement of the atoms which form the basic crystal lattice
of the zeolite remains essentially unchanged. The exchange of cations has
little, if any, effect on the zeolite lattice structures.
The high-silica SSZ-37 can be formed into a wide variety of physical shapes
and/or can be composited with other materials resistant to the
temperatures and other conditions employed in organic conversion
processes. See U.S. Pat. No. 5,254,514 for examples of such shapes and
other materials.
High-silica SSZ-37 zeolite is useful in hydrocarbon conversion reactions.
Hydrocarbon conversion reactions are chemical and catalytic processes in
which carbon containing compounds are changed to different carbon
containing compounds. Examples of hydrocarbon conversion reactions include
catalytic cracking, hydrocracking, dewaxing, and olefin and aromatics
formation reactions. The catalyst is useful in other petroleum refining
and hydrocarbon conversion reactions such as isomerizing n-paraffins and
naphthenes, polymerizing and oligomerizing olefinic or acetylenic
compounds such as isobutylene and butene-1, reforming, alkylating,
isomerizing polyalkyl substituted aromatics (e.g., meta-xylene), and
disproportionating aromatics (e.g., toluene) to provide mixtures of
benzene, xylenes and higher methylbenzenes. The high-silica SSZ-37
catalyst has high selectivity, and under hydrocarbon conversion conditions
can provide a high percentage of desired products relative to total
products.
High-silica SSZ-37 zeolite can be used in processing hydrocarbonaceous
feedstocks. Hydrocarbonaceous feedstocks contain carbon compounds and can
be from many different sources, such as virgin petroleum fractions,
recycle petroleum fractions, shale oil, liquefied coal, tar sand oil, and,
in general, can be any carbon containing fluid susceptible to zeolitic
catalytic reactions. Depending on the type of processing the
hydrocarbonaceous feed is to undergo, the feed can contain metal or be
free of metals, it can also have high or low nitrogen or sulfur
impurities. It can be appreciated, however, that in general processing
will be more efficient (and the catalyst more active) the lower the metal,
nitrogen, and sulfur content of the feedstock.
The conversion of hydrocarbonaceous feeds can take place in any convenient
mode, for example, in fluidized bed, moving bed, or fixed bed reactors
depending on the types of process desired. The formulation of the catalyst
particles will vary depending on the conversion process and method of
operation.
Other reactions which can be performed using the catalyst of this invention
containing a metal, e.g., a Group VIII metal such platinum, include
hydrogenation-dehydrogenation reactions, denitrogenation and
desulfurization reactions.
High-silica SSZ-37 can be used in a hydrocarbon conversion reactions with
active or inactive supports, with organic or inorganic binders, and with
and without added metals. These reactions are well known to the art, as
are the reaction conditions.
Hydrocracking
Using high-silica SSZ-37 catalyst which contains a hydrogenation promoter,
heavy petroleum residual feedstocks, cyclic stocks and other hydrocrackate
charge stocks can be hydrocracked at hydrocracking conditions including a
temperature in the range of from 175.degree. C. to 485.degree. C., molar
ratios of hydrogen to hydrocarbon charge from 1 to 100, a pressure in the
range of from 0.to 350 bar, and a liquid hourly space velocity (LHSV) in
the range of from 0.1 to 30.
The hydrocracking catalysts contain an effective amount of at least one
hydrogenation catalyst (component) of the type commonly employed in
hydrocracking catalysts. The hydrogenation component is generally selected
from the group of hydrogenation catalysts consisting of one or more metals
of Group VIB and Group VIII, including the salts, complexes and solutions
containing such. The hydrogenation catalyst is preferably selected from
the group of metals, salts and complexes thereof of the group consisting
of at least one of platinum, palladium, rhodium, iridium and mixtures
thereof or the group consisting of at least one of nickel, molybdenum,
cobalt, tungsten, titanium, chromium and mixtures thereof. Reference to
the catalytically active metal or metals is intended to encompass such
metal or metals in the elemental state or in some form such as an oxide,
sulfide, halide, carboxylate and the like.
The hydrogenation catalyst is present in an effective amount to provide the
hydrogenation function of the hydrocracking catalyst, and preferably in
the range of from 0.05 to 25% by weight.
The catalyst may be employed in conjunction with traditional hydrocracking
catalysts, e.g., any aluminosilicate heretofore employed as a component in
hydrocracking catalysts. Representative of the zeolitic aluminosilicates
disclosed heretofore as employable as component parts of hydrocracking
catalysts are Zeolite Y (including steam stabilized, e.g., ultra-stable
Y), Zeolite X, Zeolite beta (U.S. Pat. No. 3,308,069), Zeolite ZK-20 (U.S.
Pat. No. 3,445,727), Zeolite ZSM-3 (U.S. Pat. No. 3,415,736), faujasite,
LZ-10 (U.K. Pat. 2,014,970, Jun. 9, 1982), ZSM-5-type zeolites, e.g.,
ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48, crystalline
silicates such as silicalite (U.S. Pat. No. 4,061,724), erionite,
mordenite, offretite, chabazite, FU-1-type zeolite, NU-type zeolites,
LZ-210-type zeolite and mixtures thereof. Traditional cracking catalysts
containing amounts of Na.sub.2 O less than about one percent by weight are
generally preferred. The relative amounts of the high-silica SSZ-37
component and traditional hydrocracking component, if any, will depend at
least in part, on the selected hydrocarbon feedstock and on the desired
product distribution to be obtained therefrom, but in all instances an
effective amount of high-silica SSZ-37 is employed. When a traditional
hydrocracking catalyst (THC) component is employed, the relative weight
ratio of the THC to the high-silica SSZ-37 is generally between about 1:10
and about 500:1, desirably between about 1:10 and about 200:1, preferably
between about 1:2 and about 50:1, and most preferably is between about 1:1
and about 20:1.
The hydrocracking catalysts are typically employed with an inorganic oxide
matrix component which may be any of the inorganic oxide matrix components
which have been employed heretofore in the formulation of hydrocracking
catalysts including: amorphous catalytic inorganic oxides, e.g.,
catalytically active silica-aluminas, clays, silicas, aluminas,
silica-aluminas, silica-zirconias, silica-magnesias, alumina-borias,
alumina-titanias and the like and mixtures thereof. The traditional
hydrocracking catalyst and high-silica SSZ-37 may be mixed separately with
the matrix component and then mixed or the THC component and high-silica
SSZ-37 may be mixed and then formed with the matrix component.
Dewaxing
High-silica SSZ-37 can be used to dewax hydrocarbonaceous feeds by
selectively removing straight chain paraffins. The catalytic dewaxing
conditions are dependent in large measure on the feed used and upon the
desired pour point. Generally, the temperature will be between about
200.degree. C. and about 475.degree. C, preferably between about
250.degree. C. and about 450.degree. C. The pressure is typically between
about 15 psig and about 3000 psig, preferably between about 200 psig and
3000 psig. The liquid hourly space velocity (LHSV) preferably will be from
0.1 to 20, preferably between about 0.2 and about 10.
Hydrogen is preferably present in the reaction zone during the catalytic
dewaxing process. The hydrogen to feed ratio is typically between about
500 and about 30,000 SCF/bbl (standard cubic feet per barrel), preferably
about 1000 to about 20,000 SCF/bbl. Generally, hydrogen will be separated
from the product and recycled to the reaction zone. Typical feedstocks
include light gas oil, heavy gas oils and reduced crudes boiling about
350.degree. F.
The high-silica SSZ-37 hydrodewaxing catalyst may optionally contain a
hydrogenation component of the type commonly employed in dewaxing
catalysts. The hydrogenation component may be selected from the group of
hydrogenation catalysts consisting of one or more metals of Group VIB and
Group VIII, including the salts, complexes and solutions containing such
metals. The preferred hydrogenation catalyst is at least one of the group
of metals, salts and complexes selected from the group consisting of at
least one of platinum, palladium, rhodium, iridium and mixtures thereof or
at least one from the group consisting of nickel, molybdenum, cobalt,
tungsten, titanium, chromium and mixtures thereof. Reference to the
catalytically active metal or metals is intended to encompass such metal
or metals in the elemental state or in some form such as an oxide,
sulfide, halide, carboxylate and the like.
The hydrogenation component is present in an effective amount to provide an
effective hydrodewaxing and hydroisomerization catalyst preferably in the
range of from about 0.05 to 5% by weight.
Aromatics Formation
High-silica SSZ-37 can be used to convert light straight run naphthas and
similar mixtures to highly aromatic mixtures. Thus, normal and slightly
branched chained hydrocarbons, preferably having a boiling range above
about 40.degree. C. and less than about 200.degree. C., can be converted
to products having a substantial higher octane aromatics content by
contacting the hydrocarbon feed with the zeolite at a temperature in the
range of from about 400.degree. C. to 600.degree. C., preferably
480.degree. C. to 550.degree. C. at pressures ranging from atmospheric to
10 bar, and liquid hourly space velocities (LHSV) ranging from 0.1 to 15.
The conversion catalyst preferably contains a Group VIII metal compound to
have sufficient activity for commercial use. By Group VIII metal compound
as used herein is meant the metal itself or a compound thereof. The Group
VIII noble metals and their compounds, platinum, palladium, and iridium,
or combinations thereof can be used. Rhenium or tin or a mixture thereof
may also be used in conjunction with the Group VIII metal compound and
preferably a noble metal compound. The most preferred metal is platinum.
The amount of Group VIII metal present in the conversion catalyst should
be within the normal range of use in reforming catalysts, from about 0.05
to 2.0 weight percent, preferably 0.2 to 0.8 weight percent.
The zeolite/Group VIII metal conversion catalyst can be used without a
binder or matrix. The preferred inorganic matrix, where one is used, is a
silica-based binder such as Cab-O-Sil or Ludox. Other matrices such as
magnesia and titania can be used. The preferred inorganic matrix is
nonacidic.
It is critical to the selective production of aromatics in useful
quantities that the conversion catalyst be substantially free of acidity,
for example, by poisoning the zeolite with a basic metal, e.g., alkali
metal, compound. The zeolite is usually prepared from mixtures containing
alkali metal hydroxides and thus have alkali metal contents of about 1-3
weight percent. These high levels of alkali metal, usually sodium or
potassium, are unacceptable for most catalytic applications because they
greatly deactivate the catalyst for cracking reactions. Usually, the
alkali metal is removed to low levels by ion exchange with hydrogen or
ammonium ions. By alkali metal compound as used herein is meant elemental
or ionic alkali metals or their basic compounds. Surprisingly, unless the
zeolite itself is substantially free of acidity, the basic compound is
required in the present process to direct the synthetic reactions to
aromatics production.
The amount of alkali metal necessary to render the zeolite substantially
free of acidity can be calculated using standard techniques based on the
aluminum content of the zeolite. Under normal circumstances, the zeolite
as prepared and without ion exchange will contain sufficient alkali metal
to neutralize the acidity of the catalyst. If a zeolite free of alkali
metal is the starting material, alkali metal ions can be ion exchanged
into the zeolite to substantially eliminate the acidity of the zeolite. An
alkali metal content of about 100%, or greater, of the acid sites
calculated on a molar basis is sufficient.
Where the basic metal content is less than 100% of the acid sites on a
molar basis, the test described in U.S. Pat. No. 4,347,394 which patent is
incorporated totally herein by reference, can be used to determine if the
zeolite is substantially free of acidity.
The preferred alkali metals are sodium, potassium, and cesium. The zeolite
itself can be substantially free of acidity only at very high
silica:alumina mole ratios; by "zeolite consisting essentially of silica"
is meant a zeolite which is substantially free of acidity without base
poisoning.
Catalytic Cracking
Hydrocarbon cracking stocks can be catalytically cracked in the absence of
hydrogen using high-silica SSZ-37 at liquid hourly space velocities from
0.5 to 50, temperatures from about 260.degree. F. to 1625.degree. F. and
pressures from subatmospheric to several hundred atmospheres, typically
from about atmospheric to about 5 atmospheres.
For this purpose, the high-silica SSZ-37 catalyst can be composited with
mixtures of inorganic oxide supports as well as traditional cracking
catalyst.
The catalyst may be employed in conjunction with traditional cracking
catalysts, e.g., any aluminosilicate heretofore employed as a component in
cracking catalysts. Representative of the zeolitic aluminosilicates
disclosed heretofore as employable as component parts of cracking
catalysts are Zeolite Y (including steam stabilized chemically modified,
e.g., ultra-stable Y), Zeolite X, Zeolite beta (U.S. Pat. No. 3,308,069),
Zeolite ZK-20 (U.S. Pat. No. 3,445,727), Zeolite ZSM-3 (U.S. Pat. No.
3,415,736), faujasite, LZ-10 (U.K. Pat. 2,014,970, Jun. 9, 1982),
ZSM-5-type zeolites, e.g., ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38,
ZSM-48, crystalline silicates such as silicalite (U.S. Pat. No.
4,061,724), erionite, mordenite, offretite, chabazite, FU-1-type zeolite,
NU-type zeolites, LZ-210-type zeolite and mixtures thereof. Traditional
cracking catalysts containing amounts of Na.sub.2 O less than about one
percent by weight are generally preferred. The relative amounts of the
high-silica SSZ-37 component and traditional cracking component, if any,
will depend at least in part, on the selected hydrocarbon feedstock and on
the desired product distribution to be obtained therefrom, but in all
instances an effective amount of high-silica SSZ-37 is employed. When a
traditional cracking catalyst (TC) component is employed, the relative
weight ratio of the TC to the high-silica SSZ-37 is generally between
about 1:10 and about 500:1, desirably between about 1:10 and about 200:1,
preferably between about 1:2 and about 50:1, and most preferably is
between about 1:1 and about 20:1.
The cracking catalysts are typically employed with an inorganic oxide
matrix component which may be any of the inorganic oxide matrix components
which have been employed heretofore in the formulation of FCC catalysts
including: amorphous catalytic inorganic oxides, e.g., catalytically
active silica-aluminas, clays, silicas, aluminas, silica-aluminas,
silica-zirconias, silica-magnesias, alumina- borias, alumina-titanias and
the like and mixtures thereof. The traditional cracking component and
high-silica SSZ-37 may be mixed separately with the matrix component and
then mixed or the TC component and high-silica SSZ-37 may be mixed and
then formed with the matrix component.
The mixture of a traditional cracking catalyst and high-silica SSZ-37 may
be carried out in any manner which results in the coincident presence of
such in contact with the crude oil feedstock under catalytic cracking
conditions. For example, a catalyst may be employed containing the
traditional cracking catalyst and a high-silica SSZ-37 in single catalyst
particles or high-silica SSZ-37 with or without a matrix component may be
added as a discrete component to a traditional cracking catalyst.
Oligomerization
High-silica SSZ-37 can also be used to oligomerize straight and branched
chain olefins having from about 2 to 21 and preferably 2-5 carbon atoms.
The oligomers which are the products of the process are medium to heavy
olefins which are useful for both fuels, i.e., gasoline or a gasoline
blending stock and chemicals.
The oligomerization process comprises contacting the olefin feedstock in
the gaseous state phase with high-silica SSZ-37 at a temperature of from
about 450.degree. F. to about 1200.degree. F., a WHSV of from about 0.2 to
about 50 and a hydrocarbon partial pressure of from about 0.1 to about 50
atmospheres.
Also, temperatures below about 450.degree. F. may be used to oligomerize
the feedstock, when the feedstock is in the liquid phase when contacting
the zeolite catalyst. Thus, when the olefin feedstock contacts the zeolite
catalyst in the liquid phase, temperatures of from about 50.degree. F. to
about 450.degree. F., and preferably from 80.degree. F. to 400.degree. F.
may be used and a WHSV of from about 0.05 to 20 and preferably 0.1 to 10.
It will be appreciated that the pressures employed must be sufficient to
maintain the system in the liquid phase. As is known in the art, the
pressure will be a function of the number of carbon atoms of the feed
olefin and the temperature. Suitable pressures include from about 0 psig
to about 3000 psig.
The zeolite can have the original cations associated therewith replaced by
a wide variety of other cations according to techniques well known in the
art. Typical cations would include hydrogen, ammonium and metal cations
including mixtures of the same. Of the replacing metallic cations,
particular preference is given to cations of metals such as rare earth
metals, manganese, calcium, as well as metals of Group II of the Periodic
Table, e.g., zinc, and Group VIII of the Periodic Table, e.g., nickel. One
of the prime requisites is that the zeolite have a fairly low
aromatization activity, i.e., in which the amount of aromatics produced is
not more than about 20% by weight. This is accomplished by using a zeolite
with controlled acid activity [alpha value] of from about 0.1 to about
120, preferably from about 0.1 to about 100, as measured by its ability to
crack n-hexane.
Alpha values are defined by a standard test known in the art, e.g., as
shown in U.S. Pat. No. 3,960,978 which is incorporated totally herein by
reference. If required, such zeolites may be obtained by steaming, by use
in a conversion process or by any other method which may occur to one
skilled in this art.
High-silica SSZ-37 can be used to convert light gas C.sub.2 -C.sub.6
paraffins and/or olefins to higher molecular weight hydrocarbons including
aromatic compounds. Operating temperatures of 100.degree. C. to
700.degree. C., operating pressures of 0 to 1000 psig and space velocities
of 0.5-40 hr.sup.-1 WHSV (weight hourly space velocity) can be used to
convert the C.sub.2 -C.sub.6 paraffin and/or olefins to aromatic
compounds. Preferably, the zeolite will contain a catalyst metal or metal
oxide wherein said metal is selected from the group consisting of Groups
IB, IIB, VIII and IIIA of the Periodic Table, and most preferably gallium
or zinc and in the range of from about 0.05 to 5% by weight.
Condensation of Alcohols
High-silica SSZ-37 can be used to condense lower aliphatic alcohols having
1 to 10 carbon atoms to a gasoline boiling point hydrocarbon product
comprising mixed aliphatic and aromatic hydrocarbon. The condensation
reaction proceeds at a temperature of about 500.degree. F. to 1000.degree.
F., a pressure of about 0.5 psig to 1000 psig and a space velocity of
about 0.5 to 50 WHSV. The process disclosed in U.S. Pat. No. 3,984,107
more specifically describes the process conditions used in this process,
which patent is incorporated totally herein by reference.
The catalyst may be in the hydrogen form or may be base exchanged or
impregnated to contain ammonium or a metal cation complement, preferably
in the range of from about 0.05 to 5% by weight. The metal cations that
may be present include any of the metals of the Groups I through VIII of
the Periodic Table. However, in the case of Group IA metals, the cation
content should in no case be so large as to effectively inactivate the
catalyst.
Isomerization
The present catalyst is highly active and highly selective for isomerizing
C.sub.4 to C.sub.7 hydrocarbons. The activity means that the catalyst can
operate at relatively low temperature which thermodynamically favors
highly branched paraffins. Consequently, the catalyst can produce a high
octane product. The high selectivity means that a relatively high liquid
yield can be achieved when the catalyst is run at a high octane.
The present process comprises contacting the isomerization catalyst with a
hydrocarbon feed under isomerization conditions. The feed is preferably a
light straight run fraction, boiling within the range of 30.degree. F. to
250.degree. F. and preferably from 60.degree. F. to 200.degree. F.
Preferably, the hydrocarbon feed for the process comprises a substantial
amount of C.sub.4 to C.sub.7 normal and slightly branched low octane
hydrocarbons, more preferably C.sub.5 and C.sub.6 hydrocarbons.
The pressure in the process is preferably between 50 psig and 1000 psig,
more preferably between 100 psig and 500 psig. The liquid hourly space
velocity (LHSV) is preferably between about 1 to about 10 with a value in
the range of about 1 to about 4 being more preferred. It is also
preferable to carry out the isomerization reaction in the presence of
hydrogen. Preferably, hydrogen is added to give a hydrogen to hydrocarbon
ratio (H.sub.2/ HC) of between 0.5 and 10 H.sub.2/ HC, more preferably
between 1 and 8 H.sub.2/ HC. The temperature is preferably between about
200.degree. F. and about 1000.degree. F., more preferably between
400.degree. F. and 600.degree. F. As is well known to those skilled in the
isomerization art, the initial selection of the temperature within this
broad range is made primarily as a function of the desired conversion
level considering the characteristics of the feed and of the catalyst.
Thereafter, to provide a relatively constant value for conversion, the
temperature may have to be slowly increased during the run to compensate
for any deactivation that occurs.
A low sulfur feed is especially preferred in the present process. The feed
preferably contains less than 10 ppm, more preferably less than 1 ppm, and
most preferably less than 0.1 ppm sulfur. In the case of a feed which is
not already low in sulfur, acceptable levels can be reached by
hydrogenating the feed in a presaturation zone with a hydrogenating
catalyst which is resistant to sulfur poisoning. An example of a suitable
catalyst for this hydrodesulfurization process is an alumina-containing
support and a minor catalytic proportion of molybdenum oxide, cobalt oxide
and/or nickel oxide. A platinum on alumina hydrogenating catalyst can also
work. In which case a sulfur sorber is preferably placed downstream of the
hydrogenating catalyst, but upstream of the present isomerization
catalyst. Examples of sulfur sorbers are alkali or alkaline earth metals
on porous refractory inorganic oxides, zinc, etc. Hydrodesulfurization is
typically conducted at 315.degree. C. to 455.degree. C., at 200 psig to
2000 psig, and at a liquid hourly space velocity of 1 to 5.
It is preferable to limit the nitrogen level and the water content of the
feed. Catalysts and processes which are suitable for these purposes are
known to those skilled in the art.
After a period of operation, the catalyst can become deactivated by sulfur
or coke. Sulfur and coke can be removed by contacting the catalyst with an
oxygen-containing gas at an elevated temperature. If the Group VIII
metal(s) have agglomerated, then it can be redispersed by contacting the
catalyst with a chlorine gas under conditions effective to redisperse the
metal(s). The method of regenerating the catalyst may depend on whether
there is a fixed bed, moving bed, or fluidized bed operation. Regeneration
methods and conditions are well known in the art.
The conversion catalyst preferably contains a Group VIII metal compound to
have sufficient activity for commercial use. By Group VIII metal compound
as used herein is meant the metal itself or a compound thereof. The Group
VIII noble metals and their compounds, platinum, palladium, and iridium,
or combinations thereof can be used. Rhenium and tin may also be used in
conjunction with the noble metal. The most preferred metal is platinum.
The amount of Group VIII metal present in the conversion catalyst should
be within the normal range of use in isomerizing catalysts, from about
0.05 to 2.0 weight percent, preferably 0.2 to 0.8 weight percent.
Alkylation and Transalkylation
High-silica SSZ-37 can be used in a process for the alkylation or
transalkylation of an aromatic hydrocarbon. The process comprises
contacting the aromatic hydrocarbon with a C.sub.2 to C.sub.16 olefin
alkylating agent or a polyalkyl aromatic hydrocarbon transalkylating
agent, under at least partial liquid phase conditions, and in the presence
of a catalyst comprising high-silica SSZ-37.
For high catalytic activity, the high-silica SSZ-37 zeolite should be
predominantly in its hydrogen ion form. Generally, the zeolite is
converted to its hydrogen form by ammonium exchange followed by
calcination. If the zeolite is synthesized with a high enough ratio of
organo-nitrogen cation to sodium ion, calcination alone may be sufficient.
It is preferred that, after calcination, at least 80% of the cation sites
are occupied by hydrogen ions and/or rare earth ions.
The pure high-silica SSZ-37 zeolite may be used as a catalyst, but
generally it is preferred to mix the zeolite powder with an inorganic
oxide binder such as alumina, silica, silica/alumina, or naturally
occurring clays and form the mixture into tablets or extrudates. The final
catalyst may contain from 1 to 99 weight percent high-silica SSZ-37
zeolite. Usually the zeolite content will range from 10 to 90 weight
percent, and more typically from 60 to 80 weight percent. The preferred
inorganic binder is alumina. The mixture may be formed into tablets or
extrudates having the desired shape by methods well known in the art.
Examples of suitable aromatic hydrocarbon feedstocks which may be alkylated
or transalkylated by the process of the invention include aromatic
compounds such as benzene, toluene and xylene. The preferred aromatic
hydrocarbon is benzene. Mixtures of aromatic hydrocarbons may also be
employed.
Suitable olefins for the alkylation of the aromatic hydrocarbon are those
containing 2 to 4 carbon atoms, such as ethylene, propylene, butene-1,
trans-butene-2 and cis-butene-2, or mixtures thereof. The preferred olefin
is propylene. These olefins may be present in admixture with the
corresponding C.sub.2 to C.sub.4 paraffins, but it is preferable to remove
any dienes, acetylenes, sulfur compounds or nitrogen compounds which may
be present in the olefin feedstock stream, to prevent rapid catalyst
deactivation. Longer chain alpha olefins may be used as well.
When transalkylation is desired, the transalkylating agent is a polyalkyl
aromatic hydrocarbon containing two or more alkyl groups that each may
have from 2 to about 4 carbon atoms. For example, suitable polyalkyl
aromatic hydrocarbons include di-, tri- and tetra-alkyl aromatic
hydrocarbons, such as diethylbenzene, triethylbenzene,
diethylmethylbenzene (diethyltoluene), di-isopropylbenzene,
di-isopropyltoluene, dibutylbenzene, and the like. Preferred polyalkyl
aromatic hydrocarbons are the dialkyl benzenes. A particularly preferred
polyalkyl aromatic hydrocarbon is di-isopropylbenzene.
Reaction products which may be obtained include ethylbenzene from the
reaction of benzene with either ethylene or polyethylbenzenes, cumene from
the reaction of benzene with propylene or polyisopropylbenzenes,
ethyltoluene from the reaction of toluene with ethylene or
polyethyltoluenes, cymenes from the reaction of toluene with propylene or
polyisopropyltoluenes, and sec-butylbenzene from the reaction of benzene
and n-butenes or polybutylbenzenes. The production of cumene from the
alkylation of benzene with propylene or the transalkylation of benzene
with di-isopropylbenzene is especially preferred.
When alkylation is the process conducted, reaction conditions are as
follows. The aromatic hydrocarbon feed should be present in stoichiometric
excess. It is preferred that molar ratio of aromatics to olefins be
greater than four-to-one to prevent rapid catalyst fouling. The reaction
temperature may range from 100.degree. F. to 600.degree. F., preferably
250.degree. F. to 450.degree. F. The reaction pressure should be
sufficient to maintain at least a partial liquid phase in order to retard
catalyst fouling. This is typically 50 psig to 1000 psig depending on the
feedstock and reaction temperature. Contact time may range from 10 seconds
to 10 hours, but is usually from 5 minutes to an hour. The weight hourly
space velocity (WHSV), in terms of grams (pounds) of aromatic hydrocarbon
and olefin per gram (pound) of catalyst per hour, is generally within the
range of about 0.5 to 50.
When transalkylation is the process conducted, the molar ratio of aromatic
hydrocarbon will generally range from about 1:1 to 25:1, and preferably
from about 2:1 to 20:1. The reaction temperature may range from about
100.degree. F. to 600.degree. F., but it is preferably about 250.degree.
F. to 450.degree. F. The reaction pressure should be sufficient to
maintain at least a partial liquid phase, typically in the range of about
50 psig to 1000 psig, preferably 300 psig to 600 psig. The weight hourly
space velocity will range from about 0.1 to 10.
High-silica SSZ-37 can also be used as a selective adsorbent for
hydrocarbons and as a water-softening agent in detergents.
The present invention will be more fully understood by reference to the
following examples. They are intended to be purely exemplary and are not
intended to limit the scope of the invention in any way.
The template of Example 1 is prepared by using a Diels-Alder reaction
scheme. Two new bonds and a six-membered ring are formed in the
Diels-Alder reaction, formally a [4+2] cyclo addition of a 1,4-conjugated
diene with a double bond (dienophile). The co-pending application entitled
"Method for Preparing Crystalline Materials Using Aza-Polycyclic
Templating Agents", U.S. Ser. No. 907,419, filed Jun. 30, 1992, now U.S.
Pat. No. 5,281,407, issued Jan. 25, 1994, describes the use of Diels-Alder
chemistry to efficiently synthesize templates for zeolite synthesis. This
application is incorporated by reference in its entirety.
EXAMPLES
Example 1
Synthesis of Template
772 Grams of toluene were mixed with 99.34 grams of N-methylmaleimide.
72.40 Grams of 1,3-cyclohexadiene was added dropwise over a 2-minute
period while stirring using a magnetic stir bar. The reaction was heated
overnight and monitored by thin layer chromatography on silica (20%
EtOAc/hex). TLC indicated the reaction was complete, and therefore it was
worked up. Work up consisted of transferring a mixture to a separatory
funnel and adding 200 mL of H.sub.2 O. The pH was adjusted to .ltoreq.2
with conc. HCl which gave a slight emulsion. The phases were separated.
Another 200 mL of H.sub.2 O was added to the organic layer and the aqueous
layer was adjusted to pH .gtoreq.12 with 50% NaOH solution. Phases were
separated and the organic phase was dried over MgSO.sub.4. Solids were
filtered and the solution concentrated to yield a white solid (162.95
grams, 95.7%), designated.
A 5-liter flask was equipped with a mechanical stirrer, reflux condenser,
addition funnel, N.sub.2 inlet, and N.sub.2 outlet. This reaction was run
under N.sub.2 atmosphere. The reaction flask was charged with lithium
aluminum hydride (102.06 grams, 2.55 mol) and 2413 mL of anhydrous diethyl
ether. The addition funnel was charged with the imide from the Diels-Alder
reaction (162.85 grams, 0.85 mol) and 1206 mL of methylene chloride. The
reaction vessel was cooled in an acetone/dry ice bath (-78.degree. C.) and
the imide solution was added to the lithium aluminum hydride solution over
30 minutes. Dry ice was added to the cooling bath to control the exotherm
of the reaction. The grey heterogeneous reaction mixture was stirred at
room temperature and monitored by thin layer chromatography on silica (40%
EtOAc/hex). It was stirred overnight at room temperature.
TLC indicated the reaction was complete, therefore the reaction was worked
up. 93.2 mL of H.sub.2 O were cautiously added to the reaction mixture to
decompose the lithium aluminum hydride. This generates hydrogen. This was
followed by the slow addition of 93.2 mL of 15% of aq. NaOH. The ether
which evaporated was replaced by methylene chloride. Another 280.2 mL of
H.sub.2 O was added and the reaction mixture turned from grey to white.
This suspension was stirred for 30 minutes at room temperature, and then
the solids were removed by vacuum filtration. Solids were washed with
methylene chloride. The filtrate was transferred to a 6-liter separatory
funnel, and 300 mL of H.sub.2 O were added. The aqueous layer was adjusted
to pH .ltoreq.2 with conc. HCl. The phases were separated and another
acidic wash was performed. The combined acidic aqueous layers were then
adjusted to pH .gtoreq.12 with 50% NaOH solution and saturated with NaCl.
This was then extracted four times with 250 mL of ether. The combined
organic extracts were dried over Na.sub.2 SO.sub.4, filtered and
concentrated to yield 104.89 grams (75.6%) of the amine.
This amine was dissolved in 643 mL of chloroform in a 2-liter flask which
was equipped with a magnetic stirrer and addition funnel. This was cooled
in an ice/water bath and methyl iodide (183.9 grams, 1.28 mol) was added
over a 60-minute period. The reaction was stirred at room temperature for
4 days, then transferred to an addition funnel. The solution was added
dropwise to 2 liters of stirring diethyl ether. The yellow solids were
collected by filtration and recrystallized from hot acetone/diethyl ether
with a small amount of methanol to afford white crystals of the desired
product (180.39 grams, 92.3%). The melting point was determined to be
234.degree. C.-236.degree. C. The C, H and N values were measured as C,
47.30; H, 6.64; and N, 4.50.
Example 2
140.07 Grams of a 0.46 mol of the product of Example 1 was ion-exchanged
with 315 grams of a hydroxide ion-exchange resin (BioRad AG 1-X8) and 400
cc of water to form the hydroxide form of this template. The mixture was
stirred overnight at room temperature. The solids were removed by
filtration and washed. The solution was titrated to determine molarity.
Example 3
Synthesis of All-Silica SSZ-37
The template prepared in Example 2 (2.57 grams of a 0.58M OH solution), 1.0
gram of 1.0N NaOH, 4.34 grams of deionized water and 0.62 gram of Cabosil
M5 fumed silica were mixed in a 25 ml Teflon cup for a Parr 4645 reactor.
Seed crystals of high-silica SSZ-37 (0.03 gram, starting silica/alumina
mole ratio =200) were then added and the resulting mixture was sealed and
heated at 150.degree. C. (static) for seven days, after which a settled
product was obtained. The solids were filtered, washed thoroughly with
water, dried and determined by X-ray diffraction (XRD) to be all-silica
SSZ-37.
Example 4
Synthesis of All-Silica SSZ-37
The template prepared in Example 2 (3.68 grams of a 0.61M OH solution), 1.5
grams of 1.0N KOH, 5.61 grams of deionized water and 0.92 gram of Cabosil
M5 fumed silica were mixed in a 25 ml Teflon cup for a Parr 4645 reactor.
Seed crystals of all-silica SSZ-37 from Example 3 (0.01 gram) were then
added and the resulting mixture was sealed and heated at 160.degree. C.
and tumbled at a rate of 54 rpm. After seven days, a settled product was
obtained which was filtered, washed thoroughly with water, dried and
determined by XRD to be all-silica SSZ-37.
The table below shows XRD lines for the material prepared in this example.
______________________________________
2 .theta.
d/n 100 .times. I/I.sub.o
______________________________________
7.03 12.57 4
7.82 11.29 60
8.28 10.67 14
10.54 8.385 3 (Shoulder
12.92 6.847 7
19.18 4.623 31
20.04 4.426 20
20.42 4.346 100
22.22 3.997 70
22.66 3.921 18
23.74 3.745 14
25.88 3.440 20
26.57 3.353 19
27.12 3.285 42
______________________________________
I represents the peak height. 100 X I/I.sub.o is the relative intensity of
each peak, where I.sub.o is the intensity of the strongest line or peak.
Example 5
Synthesis of (B)SSZ-37 Using Boric Acid
The template prepared in Example 2 (5.15 grams of a 0.58M OH solution),
0.75 gram of a 1.0N NaOH solution, 4.89 grams of deionized water and 0.019
gram of boric acid were mixed together until the solids dissolved. Cabosil
M5 fumed silica (0.92 gram) was added with stirring, followed by 0.03 gram
of high-silica SSZ-37 (0.03 gram, starting silica/alumina mole ratio =200)
and the reactor was sealed and heated at 170.degree. C. and tumbled at a
rate of 43 rpm. After seven days, a settled product was obtained and
determined by XRD to be borosilicate SSZ-37. This product was found to
have a SiO.sub.2 /B.sub.2 O.sub.3 mole ratio of 71.
Example 6
Synthesis of (B)SSZ-37 Using Sodium Borate
The template prepared in Example 2 (3.68 grams of a 0.61M OH solution),
1.95 grams of a 1.0N NaOH solution, 5.16 grams of deionized water and
0.057 gram of sodium borate decahydrate were mixed together until the
solids dissolved. Cabosil M5 fumed silica (0.92 gram) was added with
stirring, followed by 0.01 gram of (B)SSZ-37 seed crystals from Example 5.
The reactor was sealed and heated at 160.degree. C. and tumbled at a rate
of 43 rpm. After 13 days, a settled product was obtained which was
filtered, washed, dried and determined by XRD to be borosilicate SSZ-37.
This product was found to have a SiO.sub.2 /B.sub.2 O.sub.3 mole ratio of
46.
XRD lines for the product of this example are provided in the table below.
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2 .theta. d/n 100 .times. I/I.sub.o
______________________________________
7.04 12.54 3
7.86 11.25 86
8.32 10.62 16
10.55 8.377 3
12.94 6.836 6
19.27 4.603 40
20.21 4.390 29
20.46 4.337 100
22.31 3.981 70
22.73 3.909 23
23.80 3.735 25
26.03 3.420 18
26.71 3.334 14
27.25 3.270 36
______________________________________
The following examples illustrate that if the template which is used to
prepare NU-87 (decamethonium hydroxide) is substituted for the template of
this invention in the type of reactions which yield all-silica SSZ-37 or
(B)SSZ-37 when the template of this invention is used, the product which
is obtained is ZSM-48.
Comparative Example A
The procedure described in Example 6 was repeated, with the exception that
2.82 grams of a 0.08M solution of decamethonium hydroxide was used as the
templating agent instead of the template of example 2. After eight days at
160.degree. C. (43 rpm), settled product was obtained which was determined
by XRD to be borosilicate ZSM-48.
Comparative Example B
Decamethonium hydroxide (2.82 9rams of a 0.8M solution), 6.47 grams of
deionized water, 1.5 9rams of a 1.0N NaOH solution and 0,037 gram of boric
acid were mixed together until the solids dissolved. Cabosil M5 fumed
silica (0.92 gram) was added with stirring, followed by 0.01 gram of
(B)SSZ-37 seed crystals (from Example 5). The reaction mixture was sealed
and heated to 160.degree. C. and tumbled at 43 rpm. After 12 days, the
solids which had formed were isolated and determined by XRD to be
borosilicate ZSM-48 with some amorphous material.
Comparative Example C
Decamethonium hydroxide (2.82 grams of a 0.8M solution), 6.47 grams of
deionized water, 1.5 grams of a 1.0N KOH solution and Cabosil M5 fumed
silica (0.92 gram) were mixed together until a homogeneous solution was
obtained. The reaction mixture was sealed and heated to 160.degree. C.
(static) for seven days, after which a settled product was obtained. The
product was determined by XRD to be ZSM-48.
Example 7
Calcination of All-Silica SSZ-37
The crystalline products of Examples 3 and 4 were subjected to calcination
as follows. The samples were heated in a muffle furnace from room
temperature to 120.degree. C. at a rate of 1.degree. C./minute. The
temperature was held at 120.degree. C. for three hours, after which the
temperature was increased to 540.degree. C. at a rate of 1.degree.
C./minute. After holding at 540.degree. C. for five hours, the temperature
was ramped at the same rate to 595.degree. C., and then held for another
five hours. A 50/50 mixture of air and nitrogen was passed over the
zeolite at a rate of 20 standard cubic feet per minute during heating.
The material obtained following this treatment was found to have a
cyclohexane micropore volume of 0.11 cc/g at p/p.sub.o =0.13.
XRD lines for the calcined product of Example 4 are provided in the table
below.
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2 .theta. d/n 100 .times. I/I.sub.o
______________________________________
7.05 12.53 6
7.94 11.13 100
8.36 10.57 22
10.63 8.313 8
12.95 6.832 8
19.29 4.598 26
20.26 4.381 7
20.64 4.301 53
22.39 3.968 20
22.78 3.901 2
23.61 3.765 2
26.10 3.412 7
26.74 3.332 6
27.34 3.259 24
______________________________________
Example 8
Treatment of All-Silica SSZ-37 With Pt
6.2 Grams of deionized water, 0.62 gram of 0.15N NH.sub.4 OH solution and
0.62 gram of calcined all-silica SSZ-37 were mixed together with stirring.
0.34 Gram of a 0.05M Pt(NH.sub.3).sub.4 (NO.sub.3).sub.2 solution was
added dropwise to the heterogeneous mixture and the resulting mixture was
stirred overnight at room temperature, filtered, and washed thoroughly
with water. The dried product was then calcined to 288.degree. C. for
three hours in air. This exchange treatment was designed to yield 0.5 wt %
Pt on the catalyst.
Example 9
Constraint Index and Activity of All-silica Pt-SSZ-37
The platinum-exchanged sample from Example 8 was pelleted at 2-3 KPSI,
crushed and meshed to 20-40, and then 0.50 grams was dried at 400.degree.
F. in air for 4 hours and cooled in desiccator. 0.47 Gram was packed into
a 3/8" stainless steel tube with alundum on both sides of the zeolite bed.
A Lindburg furnace was used to heat the reactor tube. Helium was
introduced into the reactor tube at 9.4 cc/min. and atmospheric pressure.
The reactor was taken to 800.degree. F., and a 50/50, w/w feed of n-hexane
and 3-methylpentane was introduced into the reactor at a rate of 8
.mu.l/min. Feed delivery was made via a piston pump. Direct sampling onto
a gas chromatograph began after introduction of the feed. The constraint
index value was calculated from gas chromatographic data using methods
known in the art and found to be 1.6. At 800.degree. F. and 40 minutes
on-stream, feed conversion was greater than 45%. The product selectivities
shown in the table below illustrate that Pt-all-silica SSZ-37 has very
high aromatization and dehydrogenation activity and selectivity.
______________________________________
10 40 430
minutes minutes minutes
______________________________________
Feed conversion %
57.4 47.8 32.9
Product Selectivities
3.7 2.9 1.5
C6 Isomerization
C5-Cracking 11.2 8.1 3.6
Aromatization 39.6 36.2 27.5
Dehydrogenation
28.2 35.5 49.6
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